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Cetirizine - Brand names: Allacan, Benadryl Allergy, Piriteze Allergy, Zirtek Allergy

On this page

  1. About cetirizine
  2. Key facts
  3. Who can and cannot take cetirizine
  4. How and when to take cetirizine
  5. Side effects
  6. How to cope with side effects of cetirizine
  7. Pregnancy and breastfeeding
  8. Cautions with other medicines
  9. Common questions about cetirizine

1. About cetirizine

Cetirizine is an antihistamine medicine that helps the symptoms of allergies.

It's used to treat:

Cetirizine is known as a non-drowsy antihistamine. It's much less likely to make you feel sleepy than some other antihistamines.

Cetirizine is available on prescription, but you can also buy it from pharmacies and supermarkets.

It comes as tablets, capsules and as a liquid that you swallow.

2. Key facts

  • It's usual to take cetirizine once a day. Children aged under 12 take it twice a day.
  • Cetirizine is classed as a non-drowsy antihistamine, but some people still find it makes them feel quite sleepy.
  • Common side effects include headaches, dry mouth, feeling sick, dizziness and diarrhoea.
  • Some brands of cetirizine come as capsules. These may contain soya oil. Do not take cetirizine capsules if you are allergic to peanuts or soya.
  • Some Benadryl products do not contain cetirizine, but a different antihistamine such as acrivastine.

3. Who can and cannot take cetirizine

Most adults can take cetirizine.


  • Children aged 1 and over can take cetirizine liquid if prescribed by their doctor.
  • Children aged 2 and over can take cetirizine liquid bought from pharmacies or prescribed by their doctor.
  • Children aged 6 and over can take cetirizine tablets and liquid that you buy from pharmacies and supermarkets.
  • Children aged 12 and over can take cetirizine capsules, tablets and liquid that you buy from pharmacies and supermarkets.

Who may not be able to take cetirizine

Cetirizine is not suitable for some people. To make sure it's safe for you, tell your doctor or pharmacist if you:

  • have ever had an allergic reaction to cetirizine or any other medicine
  • have an allergy to food additives
  • have an allergy to peanuts or soya – some brands of cetirizine capsules (but not tablets) contain soya
  • have kidney failure
  • have epilepsy or another health problem that puts you at risk of having seizures or fits
  • have a condition that means you have difficulty peeing
  • are due to have an allergy test – taking cetirizine may affect the results, so you might need to stop taking it a few days before the test

4. How and when to take cetirizine

If you or your child have been prescribed cetirizine, follow your doctor's instructions about how and when to take it. If it is from a pharmacy or shop, follow the instructions that come with the packet.

Dosage and strength

Cetirizine comes as tablets and capsules (10mg) and as a liquid medicine (labelled either 5mg/5ml or 1mg/1ml).

The usual dose for adults is 10mg once a day.

Doses are usually lower for people with kidney problems.


  • For children between 6 to 11 years of age, the usual dose is 5mg, twice a day. Try to leave 10 to 12 hours between doses. So, one first thing in the morning, and one before bedtime.
  • For children between 2 to 5 years of age, the dose is 2.5mg, twice a day.
  • For children between 1 to 2 years of age, your doctor will use their weight or age to work out the right dose.

How to take it

You can take cetirizine with or without food, but always take the tablets or capsules with a drink of water, milk or squash. Swallow them whole. Do not chew them.

Cetirizine liquid may be easier for children to take than tablets. The liquid medicine will come with a plastic syringe or spoon to give the right dose. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure out the right amount.

When to take it

You may only need to take cetirizine on a day you have symptoms – for example, if you have been in contact with something that has triggered your allergy, like animal hair.

Or you may need to take it regularly to prevent symptoms – for example, to stop hay fever during spring and summer.

What if I forget to take it?

Take your forgotten dose as soon as you remember, unless it's nearly time for your next dose. In this case, skip the missed dose and take your next dose at the usual time.

Do not take 2 doses to make up for a forgotten dose.

If you forget to give a dose to a child who is taking cetirizine twice a day, you can give the missed dose if it's within 4 hours of when they should have had it.

If you remember more than 4 hours after, do not give the missed dose. Instead, wait until the next dose and carry on as normal.

If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

Cetirizine is generally very safe. Taking more than the usual dose is unlikely to harm you or your child.

If you take an extra dose, you might get some of the common side effects. If this happens or you're concerned, contact your doctor.

5. Side effects

Like all medicines, cetirizine can cause side effects, although not everyone gets them.

Common side effects

The most common side effect of cetirizine is feeling sleepy and tired. This happens in more than 1 in 10 people. Talk to your doctor or pharmacist if this side effect bothers you or does not go away.

Other common side effects of cetirizine happen in more than 1 in 100 people.

Talk to your doctor or pharmacist if these side effects bother you or do not go away:

  • headaches
  • dry mouth
  • feeling sick (nausea)
  • feeling dizzy
  • diarrhoea
  • sore throat
  • sneezing or blocked and runny nose

Children are more likely to get diarrhoea, sneezing or a blocked and runny nose than adults.

Serious side effects

It's rare to have a serious side effect with cetirizine.

Call your doctor straight away if you have bruising or bleeding that's more than normal.

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to cetirizine.

Immediate action required: Call 999 now if:
  • your lips, mouth, throat or tongue suddenly become swollen
  • you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
  • your throat feels tight or you're struggling to swallow
  • your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
  • you suddenly become very confused, drowsy or dizzy
  • someone faints and cannot be woken up
  • a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)

You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.

These can be signs of a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of cetirizine. For a full list, see the leaflet inside your medicines packet.


You can report any suspected side effect using the Yellow Card safety scheme.

Visit Yellow Card for further information.

6. How to cope with side effects of cetirizine

What to do about:

  • feeling sleepy and tired – try a different non-drowsy antihistamine. If this does not help, talk to your doctor.
  • headaches – make sure you rest and drink plenty of fluids. It's best not to drink too much alcohol. Ask your pharmacist to recommend a painkiller for your headaches, but they usually go away after the first week of taking cetirizine. Talk to your doctor if your headaches last longer than a week or are severe.
  • dry mouth – chew sugar-free gum or suck sugar-free sweets.
  • feeling sick (nausea) – try taking your tablets with food. It may also help if you stick to simple meals and avoid rich or spicy food.
  • feeling dizzy – if cetirizine makes you feel dizzy when you stand up, try getting up very slowly or stay sitting down until you feel better. If you begin to feel dizzy, lie down so that you do not faint, then sit until you feel better. Do not drive, cycle or use tools or machines if you feel dizzy or a bit shaky.
  • diarrhoea – drink plenty of water or other fluids if you have diarrhoea. Speak to a pharmacist if you have signs of dehydration, such as peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
  • sore throat – if you're 16 and over, you can try gargling with an aspirin solution (1 soluble aspirin tablet dissolved in half a glass of water) or use a pain-relieving mouthwash such as Oraldene. If your symptoms last longer than a week, ask your pharmacist or doctor for advice. Children under 16 must not be given aspirin.
  • sneezing or blocked and runny nose – try a different non-drowsy antihistamine. If this does not help, talk to your doctor.

7. Pregnancy and breastfeeding

Cetirizine can be used in pregnancy. There is no good evidence that it causes harm to the baby. However, other antihistamines such as loratadine may be recommended as there is more information about its use in pregnancy.

Cetirizine and breastfeeding

If your doctor or health visitor says your baby is healthy, you can take cetirizine while breastfeeding.

There is some information available which shows that only very small amounts get into breast milk. Cetirizine has been used for many years while breastfeeding without side effects in babies.

If your baby is not feeding as well as usual, seems unusually sleepy, or if you have any other concerns about your baby, talk to your doctor, pharmacist, health visitor or midwife.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

Find out more about how cetirizine can affect you and your baby during pregnancy on the Best Use of Medicines in Pregnancy (BUMPS) website.

8. Cautions with other medicines

Some medicines can increase the chances of you having side effects with cetirizine.

Check with your pharmacist or doctor if you're taking any medicine that makes you drowsy, gives you a dry mouth, or makes it difficult for you to pee. Taking cetirizine might make these side effects worse.

Mixing cetirizine with herbal remedies and supplements

There might be a problem taking some herbal remedies and supplements alongside cetirizine, especially ones that cause sleepiness, a dry mouth, or make it difficult to pee.

Important: Medicine safety

Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.

9. Common questions about cetirizine

How does cetirizine work?

Cetirizine is a type of medicine called an antihistamine. When you come into contact with something you're allergic to, such as pollen, animal hair or fur, your body produces a chemical called histamine.

Usually histamine is a useful substance, but in an allergic reaction it causes unpleasant symptoms including itchy, watery eyes, a running or blocked nose, sneezing and skin rashes.

Cetirizine blocks the effects of histamine and reduces these symptoms.

When will I feel better?

You should start to feel better within an hour.

How long should I take cetirizine for?

It depends on why you're taking cetirizine.

You may only need to take it for a short time or as a one-off dose.

For example, if you have a reaction to an insect bite, you may only need to take cetirizine for a day or two.

You may need to take cetirizine for longer if you're taking it to prevent symptoms – for example, to stop hay fever when the pollen count is high.

Talk to your doctor or pharmacist if you're unsure how long you need to take cetirizine for.

Is it safe to take cetirizine for a long time?

Cetirizine is unlikely to do you any harm if you take it for a long time.

However it's best to take cetirizine only for as long as you need to. If you take it regularly over a long period there's a very small chance of severe itching if you stop treatment suddenly.

If you've been taking cetirizine every day for a long time, talk to your doctor before stopping it.

Can I drink alcohol with it?

It's best not to drink alcohol while you're taking cetirizine as it can make you feel sleepy.

Is there any food or drink I need to avoid?

You can eat and drink normally while taking cetirizine.

Can I drive or ride a bike with it?

Cetirizine is classed as a non-drowsy antihistamine, but it's still possible to feel sleepy after taking it.

If this happens to you, do not drive a car, ride a bike, use tools or machinery until you do not feel tired anymore.

It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive. If you're in any doubt, do not drive.

Talk to your doctor or pharmacist if you're unsure whether it's safe for you to drive while taking cetirizine. GOV.UK has more information on the law on drugs and driving.

What's the difference between cetirizine and other antihistamines?

Cetirizine is known as a non-drowsy antihistamine. That's because it's less likely to make you feel sleepy than sedating antihistamines, such as Piriton (chlorphenamine).

Most people prefer to take a non-drowsy antihistamine instead of one that makes them drowsy. An exception is when you want the medicine to make you sleepy – for example, if you have itchy skin that's keeping you awake.

What's the difference between cetirizine and other non-drowsy antihistamines?

Other non-drowsy antihistamines, such as loratadine, desloratadine, fexofenadine and levocetirizine, seem to work just as well as cetirizine.

But cetirizine seems to be more likely to make you feel sleepy than loratadine, desloratadine or fexofenadine.

Can I take it with painkillers?

Yes, you can take cetirizine together with paracetamol or ibuprofen.

Can I take 2 types of antihistamine in 1 day?

Sometimes doctors recommend that people with a severe, itchy skin rash take 2 different antihistamines together for a few days.

As well as taking a non-drowsy antihistamine during the day (such as cetirizine or loratadine), your doctor may advise that you take a drowsy antihistamine at night time if the itching is making it difficult to sleep.

Do not take 2 antihistamines together unless recommended by your doctor.

Can I take cetirizine with other hay fever treatments?

Yes, it's fine to take cetirizine together with some other hay fever treatments – for example, steroid nasal sprays (such as beclometasone (Beconase), Rhinocort Aqua and Flixonase Nasules) or eye drops.

Can I take cetirizine at higher doses than on the packet?

Your doctor may prescribe a higher dose of cetirizine (up to 4 times the usual dose) for you or your child, for a severe, itchy skin rash or swelling under the skin (angioedema).

Taking high doses of cetirizine is not suitable for everyone though. Speak to your doctor if you think cetirizine is not working for you.

Will it affect my fertility?

There's no evidence to suggest that taking certirizine will reduce fertility in either men or women.

Speak to a pharmacist or your doctor before taking it if you're trying to get pregnant.

Will it affect my contraception?

Cetirizine does not affect any type of contraception, including the combined pill and emergency contraception.

However, if cetirizine makes you vomit or have severe diarrhoea for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Check the pill packet to find out what to do.

Read more about what to do if you're on the pill and you're being sick or have diarrhoea.

Can lifestyle changes relieve hay fever?

It'll help if you do not spend too much time outside if the pollen count is high.

Tips for when you're outside

  • Do not cut grass or walk on grass.
  • Wear wraparound sunglasses to stop pollen getting into your eyes.
  • Put Vaseline around your nostrils to help trap pollen.
  • Shower and change your clothes after you have been outside to wash off pollen.

Tips for when you're inside

  • Keep windows and doors shut as much as possible.
  • Vacuum regularly and dust with a damp cloth.
  • Do not keep fresh flowers in the house.
  • Do not smoke or be around smoke as it makes hay fever symptoms worse.